Furnace electrode regulator



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W. E. MOORE FURNACE ELECTRODE REGULATOR Flled July l0, 1947 Aug. l, 1950Patented Aug. 1, 1950 FURNACE ELECTRODE REGULATOR William E Moore,Pittsburgh, Pa., assigner to Delaware Engineering Corporation,Pittsburgh, Pa., a corporation of Delaware Application July 10, 1947,Serial No. 760,031

Claims.

This invention relates to a furnace electrode regulator for electric arcfurnaces of the type in which the position of the movable electrodes isautomatically adjusted by means of a fluid operated regulator. Theregulator is controlled by apparatus which responds to variations in theelectric current supply to the furnace.

This application is a continuation of my copending application entitledFurnace Electrode Regulator, Serial No. 498,317, led August 12, 1943.

The variations of the electric current are employed through the mediumof suitable apparatus to control the power supplied to a fluid operatedmotor, the operation of which will cause the electrode to which it isconnected to move toward or awayfrom the metal charge in the furnace.

In many installations the weight of the electrode and electrode gear isquite considerable and various counterbalancing means have been used tocushion this weight so as to. avoid shocks or application of undueweight on the electrode when it meets the furnace charge, and permitprompt movement of the electrode proportional to the change in thecurrent and/or voltage of the electric power supplied to. the electrode.

Most of these arrangements have been either complicated, expensive, anddimcult to maintain, or they have `rendered unsatisfactory service,whereas the system I have 'invented requires relatively littleequipment, affords very satisfactory electrode control, is inexpensiveand substantially trouble free.

One object of my invention is to provide an automatic regulator for theelectrodes of an electric arc furnace which will ensure that asubstantially constant supply of current or power is taken from thefurnace electric supply system, and that the electrode is moved gently.

Another object is to provide apparatus which is operated by fluid power,and which is susceptible to close control.

A further object is to provide an electrode control system which issimple in construction, durable, inexpensive to construct and operate,and which affords a high load factor operation.

According to my invention, the electrode is moved by a fluid operatedcylinder piston which is automatically controlled in response tovariations in the power flowing through the electrode and the weight ofthe electrode and connected parts is balanced so that no great weightwill be transferred to the electrode.

Broadly speaking, my invention comprises a fluid motor operativelyconnected with a furnace electrode and adapted to move it to adjust thelength of the arc, means controlled by the electric condition of theelectrode current for controlling the operation of the motor, andbalancing means for the electrode.

In the accompanying drawings in which I have shown for purposes ofillustration only the presently preferred embodiment of my invention,

Figure 1 is a diagrammatic view of one embodiment of my invention;

Figure 2 is a schematic view of a type of control valve suitable for usein my invention; and

Figure 3 is a schematic view of still another type of control valvesuitable for use in my lnvention.

The drawing, Figure 1, shows an electric furnace Y I0 containing a usualcharge II ofmetal, and an electrode I2 connected to an electrode arm I3.The arm is insulated from and supported by a plunger or ram I4 which isslidably received in a fluid operated power cylinder I5. The piston andcylinder arrangement is commonly referred to as a hydraulic servo-motor.

The cylinder I5 is connected at its lower end by a pipe I6 to a controlvalve I'I. The control valve is connected -by means of a pipe I8 to thelower end of an air cushion hydraulic tank I9, sometimes referred to asthe pressure tank, and by means of the pipe 20 to the lower end ofanother air cushion fluid tank 2l sometimes referred to as theequalizing or balancing tank. The lower end of tank 2| is connected tothe tank I9 by a pipe or conduit 22 which is providedwith a pump 23driven by an electric motor 2li. A check valve 25 is locatedv in thepipe 22 between the pump 23 and the tank i9. v

The control valve I1 includes a slide valve or piston 26 which isslidably movable to regulate the supply of liquid medium from tank I9and pipe I8 to pipe I6 and cylinder I5 or the liquid exhaust fromcylinder lI5 and pipe I6 to pipe 20 and I prefer to so arrange theopenings from the regulator to the pipes I6 and I8 so that the valve 26may close both openings at the same time.

A suitable source of air under pressure, for example, an air compressor2l, supplies air at a convenient predetermined pressure above the liquidin pressure tank I9, so that the tank is only partially filled withliquid, such as a hydrocarbon oil, over which is an air cushion. Thecompressor 2l keeps the air pressure at a desired level so that theliquid is ,under a pressure sufficient to overcome the weight, frictionand inertia of the plungff. Q1? ll. and the supported equipment. The

tank I9 has a sight gauge 2l, and a valve controlled liquid supply pipe23 connected toit.

A suitable source of air under pressure, for example, an air compressor30, supplies air at a convenient pressure above the liquid, such as ahydrocarbon oil, in tank 2|. A sight gauge 3| and a valve controlledliquid supply pipe 32 is connected to the tank as shown. v The pressurein tank 2| is suilicient to substantially counterbalance the weight ofthe plunger I4 and the weight of the equipment supported thereby so thatwhen the piston 25 is positioned to allow the flow of liquid from pipe Ithrough the valve and pipe 20 to be established, the liquid will ilowfrom cylinder I to tank 2| and the plunger I4 and its connectedelectrode I2 will move slowly and gently downwardly.

The position oi the piston 28 is controlled by an automatic regulator 3lwhich is actuated in accordance with the' electric powersupply to theelectrode I2 in a manner well-known in the art. Typical ofsuchregulators'are CR4913 Amplidyne-type Electrode Regulator for Arc FurnaceControl (General Electric Co.), and the Automatic Current Regulator forElectric Arc Furnaces (Westinghouse Electric and Manufacturing Company).The construction and operation of such devices are well-known. Suiiiceit to say that if the electrode I2 approaches too closely to the chargeII, the power supply to the furnace will be unduly high, and theregulator will cause the piston 2B of valve I1 to be moved downwardly Iso as to permit liquid to pass from the pressure tank I9, pipe I8, valveI1 and pipe I6 to the cylinder I5 and cause'the electrode to be raised,thus lengthening the arc, until the power input is that desired,whereupon the piston 26 will be moved upwardly to shut of! the now frompipe i8. When the electrode is too far away from the metal charge, thecurrent will drop and the regulator 33 will lift the piston 26 so as toallow fluid to pass from the cylinder I5 through the pipe I6, valve I1and pipe 20 to the equalizing tank 2| until the power input reaches thedesired valve, whereupon the piston 26 is lowered so as to cut off thefluid discharge through pipe I6.

When the liquid is being discharged into tank 2|, the level of the fluidin the tank will rise and operate the oat valve switch or control device34 and thus start the ow of electric energy to the motor 2d which willoperate pump 23 to force the liquid through pipe 22 and check valve 25to the high pressure tank I9. The ow to tank i9 will continue so long asliquid is moved from the cylinder i5 to the tank 2|.

Instead of using air compressors 27 and 30, any other source of airsupply may be employed, for example, the ordinary shop air supply. withsuitable reducing valves. Suitable air pressures, for example, may beabout 200 p. s. i. on tank I9 and about 100 p.` s. i. on tank 2| whenthe pressure in cylinder I5 caused by the pressure of supported parts isabout 125 p. s. i. v

It is also possible to elevate the tanks I 9 and 2| so as not to requireair pressure on top of the liquid, but even in this case, the pump 23will be -required to force the liquid from-the tank 2| at a lower levelto tank I9 at a higher level.

The balancing tank or reservoir 2| is normally maintained at a pressureinsuiiicient to eifect positive operation of the servo-motor I5. Thepump 23 is used to draw fluid out of the reservoir 2| and return itthrough tank I8 and valve I'| to the line at a higher pressure.

In Figure 2 I have shown schematically 8.' 291?- trol valve 4U which maybe used in place of the control valve .|'I shown in Figure l. Thecontrol valve 40 includes a slide valve or piston 4I which is slidablymovable in a cylinder 42 to regulate the now of liquid from pipe I3 topipe I3, or the now of liquid from pipe I5 to pipe 20. The valve 4| isconnected to and controlled by the regulator 33. The control valveincludes an equalizingpipe 43 for substantially equalizing the pressurebetween the bottom of the cylinder 42 and the top thereof. The openingsof the pipes I6, Il and 20 to the cylinder 42 are so arranged that thethree openings cannot be-opened at the same time, nor can openings topipes I8 and 2li ever be opened together. Thus, fluid may ilow from pipeI3 to pipe I8 at one time. or from pipe I3 to pipe 20. or vice versa.

In Figure 3 I have shown schematically still another form of a controlvalve 50 which may be used in my invention. The valve 50 consists of acylinder 5I having a centrally disposed piston rod 52 4which isconnected to and controlled by `regulator 33. Rod 52 has two fluid-tightpiston heads 53 and 54 spaced apart on the rod 52 and slidable in thecylinder 5|. A slide valve 55 is mounted on the rod '52 betweenthe heads53 and 54 and is likewise duid-tight with respect to the cylinder walls.The pipes I6 and I8 are received in openings in the cylinder walls andare covered or uncovered by the valve 55, depending upon its position.The pipe 20 is received in an opening in the lower part of the cylinderwall as shown between the lower head 54'and the valve 55. The valve 55and the openings of the pipes I5, I8 and 20 are so arranged that uid mayflow from pipe I8 to pipe IB, or from pipe I6 to pipe 2|), but not frompipe I8 to pipe 20 or vice versa. It will be observed that this valvearrangement is balanced so that it is responsive to comparatively smallforce exerted on the piston rod 52.

In the accompanying drawings I have illustrated diagrammatically anelectrode regulating apparatus as applied to one of the electrodes of awell-known electric arc furnace, it being understood that a similarregulating device may be associated with each of the other furnaceelectrodes.

While I have described an exemplary embodiment of my invention, it is tobe understood that various changes may be made within the scope of theclaims.

I claim: l. In an electrode regulator which includes a liquid pressureoperated servo-motor having a piston for raising and lowering theelectrode, a

pressure tank for supplying liquid under pressure to the servo-motor aswill move the piston to raise the electrode and an equalizing tankcontaining liquid under pressure suiicient to substantiallycounterbalance the weight on the piston to allow the electrode to lowerthe piston and cause flow of the liquid from the servo-motor to theequalizing tank; a pump having an inlet and an outlet, a pipe connectingthe inlet directly to the liquid in the equalizing tank, a pipeconnecting the outlet directly to the pressure tank, and a controldevice in the equalizing tank responsive to the liquid level in theequalizing tank for rendering said pump operable to pump liquid underthe operating pressure existing in the equalizing tank directly from theequalizing tank and into the pressure tank.

2. In an electrode regulator which includes a liquid pressure operatedservo-motor having a piston for raising and lowering the electrode, a

`pressure tank for supplying liquid under pressure to the servo-motor aswill move the piston to raise the electrode and an equalizing tankcontaining liquid under pressure suillcient to substantiallycounterbalance the weight on the piston to allow the electrode to lowerthe piston and cause flow oi' the liquid from the servo-motor to theequalizing tank; a pipe connecting the tanks, a power operated pumpconnected in the pipe for withdrawing liquid from the equalizing tankand f forcing it at a, higher pressure into the pressure tank, and aswitch controlled by the level of liquid in the equalizing tank forcontrolling the supply of power to the pump.

' 3. For use in combination with an electrode regulator for theelectrodes of an electric arc furnace, including a liquid operatedservo-motor with a movable piston, for adjusting the length of thefurnace arc, a pressure tank containing liquid under a pressuresufficient to move the piston so as to raise the electrodes, anequalizer tank containing liquid under pressure less than the pressurein the pressure tank but sumcient w slightly less than balance theweight on the piston; a pump having an inlet and an outlet, a pipe underthe pressure vin the equalizing tank connecting the lower part of theequalizing tank to the pump inlet, a pipe connecting the pump outlet tothe pressure tank. a motor for driving the pump. and a control switchresponsive to a 1 change in the level of the liquid in the equalizingtank for controlling the flow of power to the motor.

4. For use in combination with an electrode regulator for the electrodesof an electric arc furnace, including a liquid operated servo-motor witht. movable piston, for adjusting the length ot the furnace arc, apressure tank containing liquid under a pressure suiliclent to move thepiston so as to raise the electrodes, an equalizer tank containingliquid under pressure less than the pressure in the pressure tank butsuiiicient 6 to slightly less than balance the weight on the piston; amotor driven pump having an inlet and an outlet, a pipe connecting theequalizing tank to the pump inlet, a pipe connecting the pump outlet tothe pressure tank, a check valve in one of said pipes to prevent flow ofliquid from the pressure tank to the equalizing tank, and a switchoperable by a change of level in the equallzing tank to control the flowof power to the pump.

5. The combination with a uid pressure m0- tor for regulating theposition of an electric furnace electrode, an elevating tank havingfluid therein under a higher pressure sumcient when connected with saidmotor to elevate the electrode, and an equalizing tank having iiuidtherein under a lower pressure suflcientwhen connected with said motorto counterbalance the electrode against movement; of a pump havingWILLIAM E. MOORE.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,528,510 Ritz Mar. 3, 19251,766,648 Keller June 24, 1930 1,774,213 Tagliaferri Aug. 26, 19301,895,699 Ziska Jan. 31, 1933 2,201,483 Eklund May 21, 1940

